Note that some containers have multiple valid file extensions. Typically, names like "f4v", "ogv", and "m4v" are used for audio/video files, and "f4a", "m4a", and "oga" are used for audio-only files, but this is not enforced. Similarly, "f4v" and "f4a" are often used for mp4 content designed to play in Flash Video, but this is just a convention.

3gp is compatible with mpeg4 (default) and h264 video, and aac (default) and mp3 audio. Valid values and file extensions: 3gp, 3gp2, 3g2, 3gpp, 3gpp2. Note that the 3gp format can also use a mp4 file extension.